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Old November 10th 15, 11:10 PM posted to uk.sci.weather
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Default Light pollution maps

Been looking at the light pollution maps. Someone has massaged them big time.
Just a for instance take Egypt which I can personally verify.
The whole length of the Nile in Egypt is as bright as London on the map , has nobody questioned this.
I have been on a 4 day trip from Cairo south to Aswan 300mls approx, and believe me at night the whole length of that journey, once out of Cairo was pitch black at night.
How can we believe the rest of this map, who would or why would someone do this?
Comment on this please gents.
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Old November 10th 15, 11:21 PM posted to uk.sci.weather
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Default Light pollution maps

On Wednesday, 11 November 2015 00:10:55 UTC, wrote:
Been looking at the light pollution maps. Someone has massaged them big time.
Just a for instance take Egypt which I can personally verify.
The whole length of the Nile in Egypt is as bright as London on the map , has nobody questioned this.
I have been on a 4 day trip from Cairo south to Aswan 300mls approx, and believe me at night the whole length of that journey, once out of Cairo was pitch black at night.
How can we believe the rest of this map, who would or why would someone do this?
Comment on this please gents.


Can't - no map. You should have provided a link.

Tudor Hughes, Warlingham, Surrey.
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Old November 11th 15, 07:56 AM posted to uk.sci.weather
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Default Light pollution maps

On 11/11/2015 00:10, wrote:

Been looking at the light pollution maps. Someone has massaged them big time.


Unless you give us a link it is hard to comment on the veracity of what
you claim. But looking at the maps that I know of the vast majority of
Africa is as dark as dark can possibly be and only the core of Cairo is
even remotely close to London levels of light pollution.

There is some tweaking of the transient oceanic light pollution to
remove squid fisheries and other shipping with bright lights at sea.

Just a for instance take Egypt which I can personally verify.
The whole length of the Nile in Egypt is as bright as London on the map ,
has nobody questioned this.


No it isn't!

I have been on a 4 day trip from Cairo south to Aswan 300mls approx,
and believe me at night the whole length of that journey, once out of
Cairo was pitch black at night.
How can we believe the rest of this map, who would or why would someone do this?
Comment on this please gents.


They haven't you are completely misinterpreting the map.

Green corresponds to fairly reasonable dark skies where you can expect
to easily see the milky way - about as dark as in the North York moors.

Blue corresponds to the very best dark skies available in the UK short
of going to the north of Scotland. And nowhere in the UK gets down to
black whereas forty miles from the Nile and skies are pristine.

See:

http://www.lightpollution.it/worldatlas/pages/fig4.htm (Europe)

vs

http://www.lightpollution.it/worldatlas/pages/fig5.htm (Africa)

Cairo doesn't even make it quite into the red. Central London is white!

It is perhaps easier to understand in the number of stars visible map:

http://www.lightpollution.it/dmsp/numstar.html

Most of the Nile journey will be in the ~1000 stars visible regime.
In central London (except immediately after a cold front deluge has
swept the air clean) you will be very lucky to see 200 stars.

--
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Martin Brown
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Old November 11th 15, 11:27 PM posted to uk.sci.weather
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Default Light pollution maps

https://www.google.co.uk/search?scli...ap_YaUdNVzM%3A

This is the link I have been looking at, while not strictly weather related it gives an illustration of Internet disinformation.

After you look at this please comment on Egypt as per my origonal comments.
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Old November 12th 15, 06:21 AM posted to uk.sci.weather
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Default Light pollution maps

On Wed, 11 Nov 2015 16:27:03 -0800 (PST)
wrote:

https://www.google.co.uk/search?scli...ap_YaUdNVzM%3A

This is the link I have been looking at, while not strictly weather
related it gives an illustration of Internet disinformation.

After you look at this please comment on Egypt as per my origonal
comments.


This link is just a record of your search and not a link to any
particular site. You need to open the site itself and then copy the
link.
Top of the search list as I see it is this one,
http://www.lightpollutionmap.info/#z...yers=B0TFFFFTT

Was this the one you meant?

--
Graham P Davis, Bracknell, Berks. [Retd meteorologist/programmer]
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I wear the cheese. It does not wear me.
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Old November 12th 15, 07:00 AM posted to uk.sci.weather
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Default Light pollution maps

On 12/11/2015 00:27, wrote:
https://www.google.co.uk/search?scli...let-gws&site=&
source=hp&q=light+pollution+map+world&oq=light+po llution+map+world&
gs_l=tablet-gws.3..0j0i22i30l2.3336.21034.0.21569.27.16.1.10.1 1.0.
150.1581.11j5.16.0....0...1c.1.64.tablet-gws..0.27.1646.1P7d6D93naw
#imgrc=6aAap_YaUdNVzM%3A

This is the link I have been looking at, while not strictly weather
related it gives an illustration of Internet disinformation.


****wit. That is your google search string and not a specific URL.

It is you who are the source of internet disinformation.

After you look at this please comment on Egypt as per my origonal comments.


You have already been told why the map shows the Nile region as light
pollution coded green which is a pretty dark sky by British standards.

--
Regards,
Martin Brown
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